At present, a variety of network services are provided for payment by systems consisting of servers and clients. Some of these pay network services perform service management with machine IDs (terminal IDs) and user IDs, and provide a variety of services for payment via networks by charging user IDs registered in specific machines. Others provide services by charging user IDs registered in specific users' machines such as personal computers in which given special terminal software is installed.
A client (a terminal or terminal software) is sold with a product warranty. The purpose of the warranty is, as its name implies, to provide a guarantee if something is wrong with a product. In addition to a conventional warranty in the form of a paper card that comes with a product, an electronic warranty has been proposed. For instance, Japanese Laid-Open Patent Application No. 10-105626 (An electronic warranty issuance and management method and system) discloses a method of electronically sharing information related to the warranty of a sold product among the manufacturer, distributor, and purchaser of the product.
Generally, in network services, it is a key to the improvement of business performance for a server to obtain many clients and have the clients use many network services. For that purpose, first of all, a large amount of attractive information should be provided, and it is necessary to obtain a large number of unspecified users on networks.
On the other hand, each user needs a special client in terms of hardware and software for information transmission to and reception from the server, so that the clients are expected to be distributed and spread effectively among the users.
Therefore, in the network services, there is a general tendency to sell the clients at lower prices, and in some cases, special terminal software used in personal computers, which can be provided on-line via networks, is distributed free. That is, income from the network services does not depend on income from the sales of the clients that are tools for connection, but the network services profit by having their menus used. Accordingly, in many cases, the server can expect an income from its services continuously for a long period of time.
For the above-described reason, payback is often provided to client distributors, who distribute clients for free or at low prices, as an incentive to sales network expansion and client distribution. Conventionally, the payback has been made only by an easy method such as a distributor's own request. For instance, a distributor has been paid back a certain commission on the sales of one client.
However, the problem has been an effective means of realizing mass distribution and sales of clients as a means of obtaining more customers and promotion of using more network services continuously for a long period of time, and a solution to the problem has been sought.